Process for controlling vegetation



- Gideon D.

2,876,088 PROCESS FOR CONTROLLING VEGETATION Hill and Silas S. Sharp,Wilmington, and Dale E. Wolf, Hockessin, Del., assignors to E. I. duPont de Nemonrs and Company, Wilmington, Del., a corporation of DelawareNo Drawing. Application November 26, 1954 Serial No. 471,516

2 Claims. (CI. 11-25 This invention relates to processes for the-controlof weeds in soil of high adsorptivity. More particularly, it relates tomethods in which both a herbicidally active aromatic aliphaticsubstituted urea and a high boiling hydrocarbon oil, as morespecifically set out hereinafter, are applied to such soils.

Varied classes of substituted ureas are known to be useful for thecontrol of unwanted vegetation. Some of these are set forth, forexample, in U. S. Patents 2,655,444, 2,655,445, and 2,655,447. Many ofthe substituted ureas are highly effective in soil sterilant use for alarge variety of soil types. By soil sterilant we mean a material thatis effective for giving complete kill of plant growth for an extendedperiod. There has existed a problem, however, in obtaining effectivesoil sterilant use of urea herbicides on soils of high adsorptivityspecifically on soils having a k-value greater than about 15. Such soilsexist along many railroad right-of-ways, and also in and aroundlumbering operations and industrial areas or parking lots having a highcontent of carbonaceous material such as cinders.

The term soil is used herein in its broadest sense to mean any solidsubstance or medium in which plants can take root and grow. In otherwords, it includes such varied things as railroads ballast including itscontaminants, cinders, muck soils, as well as earth surface material ofthe more conventional kind.

The processes of the invention can be practiced with any of theherbicidally active substituted ureas. Preferably the ureas employed arethose represented by the where X is hydrogen or halogen; Y is hydrogenor an aliphatic group of l to 4 carbon atoms; n is a positive integerfrom 1 to 4 inclusive; m is a positive integer from 1 to 3 inclusive;the sum of n and m being from 2 to 5 inclusive; R and R" are hydrogen,formyl or an aliphatic group of 1 to 4 carbon atoms; R is methyl orethyl; with the proviso that not more than one of R and R" is formyl.

Illustrative of the preferred aromatic aliphatic ureas employed in theprocesses of the invention are:

3-(p-chlorophenyl)-l-methyl urea 3-(3,4-dichlorophenyl)-l,l-dimethylurea3-(p-chlorophenyl)-1,l-dimethylurea 3-phenyl-l,l-dimethylurea3-(3-chloro-p-tolyl)-1,l-dimethylurea 3-(3-chloro-4-sec.butylphenyl)-l,1-dimethylurea 3-( 3 ,4'dichlorophenyl) -1,1-diethylurea3-(p-tolyl)-1,1-dimethylurea 3-(3,4-dimethylphenyl)-1,1-dimethylnrea3-(3,4-dichlorophenyl)-l-methyll-sec. butylurea3-(3,4-dichlorophenyl)-1-methyl-1-N-butylurea 1(3,4-dich1orophenyl)-1,3'dimetbylurea 23-(p-chlorophenyl)-1,1,3-trimethylurea3-(3,4-diehlorophenyl)-1,l,3-trimethylurea3-(m-chlorophenyl)-1,1-dimethylurea3-(2,4,5-trichlorophenyl)-l,l-dimethylurea3-(3,4-dichlorophenyl)-3-formyl-1,1-dimethylurea3-(3,4-dichlorophenyl)-l-formyl-1-methylurea3-(p-chlorophenyl)-1-formy1-1-methylurea 3-(m-chlorophenyl)-1-formyll-methylurea 3-(3-chloro-4-isopropylphenyl)-1,1-dimethylureaThe high boiling hydrocarbon oils employed in the processes of theinvention are those generally characterized by having a boiling range of400 to 700 F. at atmospheric pressure and an ASTM sulfonation index ofnot more than about by volume. Most preferred are those hydrocarbon oilshaving a sulfonation index of from 50 to 70%.

Illustrative of suitable high boiling hydrocarbon oils are a productcurrently sold under the designation of L-8764" by Standard Oil Companyof Indiana, and a product currently marketed under the designation of"LHO- by Lion Oil Company.

In carrying out the processes of the invention, the substituted urea andthe oil can be applied simultaneously from a mixture or solution of theurea compound and the oil or alternatively it can be applied separatelyin point of time, in which latter case it would ordinarily be preferableto apply the oil first.

The amounts ofoil and substituted urea applied will, of course, varywidely depending upon the particular soil type, the weed probleminvolved, and the particular substituted urea employed. In general, theoil will be employed in amount corresponding to at least 25 gallons peracre. Ordinarily, it is unnecessary to apply more than about 250 gallonsper acre under anytcircumstances altho larger amounts can be used ifcost is not a consideration. The substituted ureas will ordinarily beapplied in amounts corresponding to at least 5 pounds per acre and moregenerally 10 pounds per acre or more with a practical economic top limitof about pounds per acre.

The urea herbicide to be applied, either separately or in admixture withthe oil, can be admixed with other pest control adjuvants orconditioning materials in the conventional manners. Thus the materialcan be in the form of a powder, a solution, an oil suspension, or anemulsifiable composition. It will be understood also that the highboiling hydrocarbon oil uad need not be pure, that is, it may containsubstantial amounts of lower or higher boiling materials as well asnon-hydrocarbon such as the usual sulfur and other constaminants foundin petroleum distillates.

As mentioned heretofore, the soils upon which the methods of theinvention are practiced are those having a high adsorptivity, morespecifically those specified as having a k-value greater than about 15.By k-value, we mean the concentration of the substituted urea compoundin parts per million on the soil in equilibrium with an aqueous solutionof the substituted urea in a concentration of one part per million. Morespecifically, k-value refers to the constant k in the Freundlichadsorption equation:

where c is the concentration in parts per million of the substitutedurea in solution in equilibrium with the adsorbent, x is the quantity inmicrograms of the sub stituted urea adsorbed on m grams of soil, n, likek, is a constant and is readily determined for each system bydetermining at least two equilibrium values of x and c and solving theabove equation by conventional graphical procedures.

Methods of the invention are further illustrated by the followingdetailed examples.

Example 1 A high boiling hydrocarbon oil and 3-(p-chlorophenyl)'l,1-dimethylurea were applied both alone and in combination in theamounts shown in the tabulation below to a railroad ballast having ak-value of 31.

The oil employed in this example is characterized as follows:

Distillation range (ASTM method) 472-720" F.

Sulfonation index 64% by volume. Hydrogen to carbon ratio 1.62.

Refractive index 1.5108 at 25 C. Specific gravity 0.8894. Bromine number36.8.

The following table which shows the applications of the severalmaterials and their dosagesalso shows the measure of herbicidal action.

Urea Herb- Oil in ieide in Gallons Herbieidal Action 26 Days Pounds PerAcre After Treatment Per Acre 1 25 104. 9 substantially complete kill. 225 None slight to moderate injury. 3 None 104. 9 some slight injury atleaf tips.

In this experiment, the methods and materials used are the same as inExample 1 except that diesel oil replaces the oil used in that example.The results obtained are shown in the following tabulation.

Urea Herb- Oil in icide in Gallons Herbicidal Action 26 Days Pounds ForAuto After Treatment For Acre 1 30 209.8 substantially complete kill. 230 None moderate plant in ury. 3 None 209. 8 no injury.

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed for obvious modifications will occur to those skilled in theart. Thus any departure from the description herein which conforms tothe principles of the invention is intended to be included within thescope of the claims below.

We claim:

1. A process for the control of vegetation in soil having anadsorptivity equivalent to a k-value above about 15 which comprisesapplying to said soil at an acre rate of from about 5 to 100 pounds of aherbicidally active aromatic aliphatic urea mixed with from about 25 to250 gallons of a hydrocarbon oil boiling in the range of 400 to 700 F.at atmospheric pressure and having a sulfonation index of no more thanabout by volume.

2. A process for the control of vegetation in soil having anadsorptivity equivalent to a k-value above about 15 which comprisesapplying to such soil one or more herbicidally active aromatic aliphaticureas represented by the formula:

Yin-i R B."

where X is selected from the group consisting of hydrogen and halogen; Yis selected from the group consisting of hydrogen and an aliphatic groupconsisting of 1 to 4 carbon atoms; n is a positive integer from 1 to 4inclusive, m is a positive integer from 1 to 3 inclusive, the sum of nand m being from 2 to 5 inclusive; R and R" are selected from the groupconsisting of hydrogen, formyl, and an aliphatic group of from 1 to 4carbon atoms, with the proviso that not more than one of R and R" isformyl; and R is selected from the group consisting of methyl and ethyl;said ureas being mixed with a hydrocarbon oil boiling in the range of400 to 700 F. at atmospheric pressure and having a sulfonation index notgreater than 90% by volume, said mixture of urea and oil being appliedat the rate of from about 5 to pounds of urea and from about 25 to 250gallons of oil per acre.

References Cited in the file of this patent UNITED STATES PATENTS2,655,446 Todd Oct. 13, 1953 2,704,246 Goodhue et a1. Mar. 15, 19552,732,291 Davie Jan. 24, 1956

1. A PROCESS FOR THE CONTROL OF VEGETATION IN SOIL HAVING ANADSORPTIVITY EQUIVALENT TO A K-VALUE ABOVE ABOUT 15 WHICH COMPRISESAPPLYING TO SAID SOIL AT AN ACRE RATE OF FROM ABOUT 5 TO 100 POUNDS OF AHERBICIDALLY ACTIVE AROMATIC ALIPHATIC UREA MIXED WITH FROM ABOUT 25 TO250 GALLONS OF A HYDROCARBON OIL BOILING IN THE RANGE OF 400 TO 700* F.AT ATMOSPHERIC PRESSURE AND HAVING A SULFONATION INDEX OF NO MORE THANABOUT 90% BY VOLUME.